Chef Julian Barsotti's colossal, impressive dish requires two days of preparation; it can all be achieved a day in advance of baking. Some of the components (whose recipes are all linked below) can be made up to three days in advance. The lasagna sheets may be purchased at Civello's Raviolismo. For the heavy, 5 1/2 quart pot, an enameled cast-iron Dutch oven is ideal; Barsotti uses a Staub.

Serves 12 to 16.

Ingredients

3 tablespoons butter

4 30-inch lasagna sheets (see recipe; if you're using purchased ones, par-cook them according to the directions for the home-made sheets)

Instructions

1. Carefully butter the entire interior of a heavy, 5½-quart pot (about 10 inches in diameter and 4½ inches deep). Be sure to butter the interior thickly and completely, or the pasta skin will stick and the timpano will break apart when it is unmolded.

2. Lay a lasagna sheet into the pan, placing it so that one edge touches the bottom edge of the pot and each side of the sheet is an even length, covering the sides of the pot and draping out over the edges (you will fold the ends over the top after the timpano is filled).

3. Measure the uncovered part of the bottom of the pot and cut another lasagna sheet lengthwise, so it is wide enough to completely cover the exposed portion of the bottom of the pot and overlap the first lasagna sheet by ½ inch. Lay the second sheet in, pressing the sheets together to seal and pressing them tightly along the sides and bottom of the pot.

4. Drape a third sheet crosswise over the first two, pressing it into the other sheets and to the sides of the pot. Cut the remaining lasagna strips into pieces wide enough to patch any gaps between the pasta sheets and also overlap the other sheets by ½ inch. Press all of the pasta sheets together so they form a tight seal. It is important that no part of the interior of the pot is exposed — if it is not completely covered by the pasta, the timpano will leak and cause the pasta to burn and stick to the pot.

Clockwise from top left: Barsotti makes Bolognese; rolling out a pasta sheet; dividing the penne in bechamel; the 21-laver creation, ready for the oven (Tom Fox/Staff Photographer)

20. Carefully fold the ends of the lasagna sheets over the top, starting with the smaller strips used for patching. Tuck in loose ends, and press all pasta sheets together to form a good seal. If you see any gaps between the pasta sheets, patch them now. The height of the timpano should be even with the top of the pot.

21. Cover and store in the refrigerator until you are ready to bake. (It can be assembled up to a day in advance.)

22. Heat the oven to 375 degrees. Bake the timpano, covered, for 30 minutes. Uncover it and bake 1 hour more. Remove from the oven and let rest for 1 hour before unmolding.

23. For maximum drama, unmold the timpano at the table: Place a wooden cutting board across the top of the pot and invert the timpano. Set the board on the table, give the bottom of the pot a few good whacks and carefully lift the pot away from the timpano.